On October 18 and 19, the Chicago Architecture Foundation (CAF) will hold its fourth-annual architecture festival—Open House Chicago (OHC). Open House is a free, citywide, behind-the scenes peek at 150 of the city’s greatest buildings. In 2013, more than 55,000 individuals made 194,000 trips to the buildings included in the festival. Whether you are an architecture buff, history enthusiast or a curious urban adventurer, Open House is an annual “must-see” event.